Megachile

“ All the Leaf-cutters have the same talent for making the lids of their pots.
A less mysterious question than this geometrical problem is that of the materials. Does each species of Megachile keep to a single plant, or has it a definite botanical domain wherein to exercise its liberty of choice? The little that I have already said is enough to make us suspect that the insect is not restricted to one plant; and this is confirmed by an examination of the separate cells, piece by piece, when we find a variety which we were far from imagining at first. ”

“ I see Anthidia laboriously provide numerous bales of cotton to stop galleries wherein never an egg was laid; I see Mason-bees build and then religiously close cells that will remain unvictualled and uncolonized.
The long and useless barricades then belong to the last hours of the Megachile's life, when the eggs are all laid; the mother, whose ovaries are exhausted, persists in building. Her instinct is to cut out and heap up pieces of leaves; obeying this impulse, she cuts out and heaps up even when the supreme reason for this labour ceases. ”

“ The males of Cœlioxys can be readily distinguished from those of Megachile, by the spinose apex of their abdomen. In Megachile, general habit will bring the males within the precincts of their genus, as well as their largely dilated anterior tarsi in some of the species. ”

“ The Black-tipped Leaf-cutter (Megachile apicalis, SPIN.) has for her abode the cells of the Mason-bee of the Pebbles and the ruined nests of the Osmiae and Anthidia in the Snail-shells. I have not known her to use any other materials than the wild briar and the hawthorn.
Incomplete though it be, this list tells us that the Megachiles do not have exclusive botanical tastes. Each species manages extremely well with several plants differing greatly in appearance. The first condition to be fulfilled by the shrub exploited is that it be near the nest. ”

“ The interesting habits of the Leaf-cutting, or Tailor bee (Megachile) , have always attracted attention. This bee is a stout, thick-bodied insect, with a large, square head, stout, sharp, scissors-like jaws, and with a thick mass of stout, dense hairs on the under side of the tail for carrying pollen, as she is not provided with the pollen-basket of the Honey and Humble bees.
The Megachile lays its eggs in burrows in the stems of the elder (Fig. 24) , which we have received from Mr. ”

“ The leaf-stalk is clipped with the scissors and, without more ado, the Megachile retires the richer by a first-rate bit of material.
Split up into their component parts, two cells give me altogether eighty-three pieces of leaves, whereof eighteen are smaller than the others and of a round shape. The last-named come from the lids. If they average forty-two each, the seventeen cells of the nest represent seven hundred and fourteen pieces. These are not all: the nest ends, in the Capricorn's vestibule, with a stout barricade in which I count three hundred and fifty pieces. ”

“ Everything suits them, exotic or native, rare or common, provided that the bit cut out be easy to employ. It is not the general aspect of the shrub, with its fragile or bushy branches, its large or small, green or grey, dull or glossy leaves, that guides the insect: such advanced botanical knowledge does not enter into the question at all. In the thicket chosen as a pinking-establishment, the Megachile sees but one thing: leaves useful for her work. ”

“ From the petals of the flowers of this plant they cut out semicircular pieces, precisely as is done by Megachile with the more rigid leaves of shrubs and trees, and convey them home and line their nests with them, just as is practised by that genus with those leaves,—with this difference merely, that a sufficient portion of the upper edge of the pieces of the petals used is left projecting, for the purpose of forming a covercle to the nidus, and which, when filled with provender and the 294egg deposited, is refolded over it and covered in, and it is closed up with earth. ”

“ Later, when it spins its cocoon, the larva infuses a little of its fluid silk into the gaps and solders the pieces to one another, especially the inner ones, so much so that the insecure bag in due course becomes a solid casket whose component parts it is no longer possible to separate entirely.
The protective sheath, which is also a framework, is not the work of the mother. Like the great majority of the Osmiae, the Megachiles do not understand the art of making themselves a home straight away: they want a borrowed lodging, which may vary considerably in character. ”

“ Thus, the male artisan bees, although not assisting in the labour of constructing the apartments, have similarly dilated mandibles to those of their females. So also, in the form of the abdomen, the Nomadæ are like the Andrenæ and Halicti, upon which they are chiefly parasitical. 49Melecta resembles Anthophora; Cælioxys has the form of Megachile, both in the hollowed base of the abdomen and the peculiar manner the latter has of raising its extremity,—something like a Staphylinus. ”

“ Thus, it appears to be only the species of this division with the dilated tarsi that are exposed to such incursions, there being no record of parasites frequenting the division in which the males have simple anterior tarsi. Besides this bee-parasite, they are also subject to the attacks of some dipterous insect, whose larvæ destroy the larvæ of the Megachile. Much difficulty exists in separating the females of some of the species from each other ”

“ Fabre states that these Anthidium, as well as Megachile, will continue to construct cells when they have no eggs to place in them; in such a case it would appear from his remarks that the cells are made in due form and the extremity of the reed closed, but no provisions are stored in the chambers.
The larva of the Anthidium forms a most singular cocoon. We have already noticed the difficulty that arises, in the case of these Hymenopterous larvae shut up in small chambers, as to the disposal of the matters resulting from the incomplete assimilation of the aliment ingested. ”

“ Nor do botanical conditions seem to influence them beyond, the probability of their dissemination being restricted to the special diffusion of the families of such plants whose genera and species they frequent with us.
Thus, inhabiting Northern Europe we find in—
Lapland. Cilissa; Anthophora; Epeolus; Megachile; Chelostoma; Heriades; Osmia; Apathus; Bombus; Apis.
Finland. Colletes; Prosopis; Cilissa; Anthophora; Nomada; Epeolus; Stelis; Cœlioxys; Megachile; Anthidium; Chelostoma; Heriades; Osmia; Apathus; Bombus; Apis.
Sweden. All our genera except Sphecodes; Halictus; Macropis; Anthocopa. ”

“ If we can trace peculiarities of structure to efficient reasons, differences of form may be rationally concluded as having their cause too, even if it elude our explanatory research. Although the reason of peculiar structure is not always obvious, it must exist, though undetected; as, for instance, why in some bees, as in Megachile, Osmia, Chelostoma, Anthidium, etc., the under side of the abdomen should be furnished densely with hairs to carry their provision of pollen home to their nest, when in other 48bees, as in Dasypoda, Panurgus, Eucera, Anthophora, etc. ”

“ This trifling variation is the fulcrum for which Archimedes clamoured in order to lift the world with his system of levers. The Megachiles offer us one and a very great one: the indefinite variation of their materials. What will the theorists' levers lift with this fulcrum? Why, nothing at all! Whether they cut the delicate petals of the geranium or the tough leaves of the lilac-bushes, the Leaf-cutters are and will be what they were. ”

“ The petal may to a certain extent, in connection with the pistil, serve as support for the insect. Todd and Robertson observed only humblebees visiting the flowers. The writers obtained:
Apis mellifica Linn. Lake View, August 7. Seven specimens. Agapostemon texanus Cress. Lake View, August 7. Mellisoides bimaculata (St. Farg) Lepl. Lake View, August 7. Megachile petulans Cress. Lake View, August 7. Bombus separatus Cress. Lake View, August 7.
As in the case of Solanum, it will be seen that the collecting period extended over a very short period of time. ”

“ It is nevertheless quite possible that such may exist, but that it is disguised by the faulty manner in which the skeleton is put up. It strikes me as little probable that two animals which agree so well in the principal particulars of their organization should differ so much in one of the most important. The Megatherium has been proved by later discoveries to possess the same powerful tail as the Megalonyx, and as it corresponds also with the latter entirely in the conformation of its extremities, the same difficulties present themselves against the supposition of its having been a burrower. ”

“ Stranger still, perhaps, is the range of Plutellus and Megascolides, of which the former, chiefly found in Australia and Tasmania, not only extends its habitat to Ceylon but also to North America; it is there represented by Eisen's species Argilophilus marmoratus, referred by him, and not unnaturally, to a distinct genus, but placed by Michaelsen in Plutellus. Megascolides is Australian and from the North Island of New Zealand, where its species were regarded by Benham as of a distinct genus, Tokea. There is also one form, Megascolides americanus, in the western region of North America. ”

“ In the post-pliocene formations of South Carolina, exposed along the bed of the Ashley River, remains of the megatherium, megalodon, and other gigantic extinct mammals, occur, not only associated with existing species peculiar to the American continent, but also apparently with others hitherto believed to have been domesticated and introduced for the first time by modern European colonists. ”

“ In some places, the rock deposits are marine, and one might find fossil fishes. Some rocks were deposited near great forests and one might only [Pg 274] find fossil leaves and ferns, with, perhaps, primitive insects something like dragon-flies, called Meganeura, a foot and a half long. In many places the rocks hold sea creatures from five to fifteen million years old. If every youngster in the United States would look around for fossils when he got the chance, we’d probably find more new species in a year than we find now in ten years. ”

“ With a length of perhaps thirty feet, capable of free and rapid movement on land, with strong hind limbs, short head, with long pointed teeth, and formidable claws to its feet, the Megalosaur must have been without a rival among the carnivorous reptiles on this side of the world. It probably walked for the most part on its hind legs, as depicted in our illustration, and Professors Huxley and Owen, on examining the bones in the Oxford Museum, were much impressed with the bird-like character of some parts of the skeleton, showing an approach to the ostrich type. ”

“ The rostrum is longest (average 7.7 mm.) in specimens from the vicinity of the type locality of R. m. aztecus, but is relatively long (7.5-7.6 mm.) in populations from as far north as northeastern Colorado and southwestern Nebraska. An average greater occipitonasal length (greatest length of skull) in specimens from the south and southwest results mostly from the longer rostrum.
Recognition of two subspecies of R. megalotis on the central Great Plains seems justified on the basis of the geographic variation discussed above. One subspecies, for which the name R. m. ”

“ If the astragalus, which I have referred with doubt to the Megalonyx, do not actually belong to that genus, it is evidently part of a very closely allied species. Now this astragalus, as we have seen, resembles most closely that of the Megatherium; and since we may infer that the calcaneum, scaphoides, and cuboides had a like correspondence, the inclination of the sole of the foot inwards must have been very slight, as I have determined from examination of the structure and co-adaptation of those bones in the incomplete skeleton of the Megatherium in the London College of Surgeons. ”

“ An action going on, on every side of us, and yet barely appreciable, might surely be carried a little further, without exciting our observation. Who could feel any great surprise at hearing that the Megalonyx was formerly rare compared with the Megatherium, or that one of the fossil Monkeys was few in number compared with one of the now living Monkeys? and yet, in this comparative rarity, we should have the plainest evidence of less favourable conditions for their existence. ”

“ The great size of the bones of the Megatheroid animals, including the Megatherium, Megalonyx, Scelidotherium, and Mylodon, is truly wonderful. The habits of life of these animals were a complete puzzle to naturalists, until Professor Owen [4] solved the problem with remarkable ingenuity. The teeth indicate, by their simple structure, that these Megatheroid animals lived on vegetable food, and probably on the leaves and small twigs of trees ”

“ Differential selective pressure, therefore, theoretically would be less between eastern and western populations of R. megalotis than in an upland-inhabiting species. In any event, specimens from western Nebraska, Wyoming, northern Colorado, and adjacent areas average only slightly paler dorsally than specimens in corresponding pelages from the eastern parts of Nebraska and Kansas, and many individuals from the two areas can be matched almost exactly. ”